Hardenable alloy



Patented dune Z6, i926.

unuTanf *sTTasf aereas@ eaTauT @Tarea c REGINALD SCOTT DEAN, OF LA GRANGE, ILLINOIS, SSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, 03F NEW YORK, N. Y., A.. CORPORATION OlE NEW YORK.

HARDENABLE ALLOY.

l This invention relates to hardenable alloys, and more especially to methods of producing the same.

rlhe object of the invention is to provide a practical and efficient method for producing age hardenable alloys havingdiferent.

\ adding to lead matter which will be soluble in lead and having a solubility which will vary with a change in temperature, the lead alloy can be treated by aprocess. to enhance its properties to produce a roduct which is resistant to corrosion, is p astio, but has a greater hardness, toughness, tensile strength and resistance to abrasion and related mechanical properties.

rlhe copending'application above referred to also discloses that the proper length of time and temperature of the heating or solution forming step, quenching or supersaturating step,land aging stepk of the process wherein the alloy is allowed to assume a more stable state, together with the proper proportions of the lead and antimony, would vary depending upon the properties desired in the valloyand also depending upon the uses to which thenalloy is put. The present invention is based on further experiments in which solid lead-antimony alloys have been allowed to become supersaturated in cooling media having different heat absorption properties than water at room temperature, the specific quenching medium delined Y. in the foregoing application. Results obtained from these experiments establish the fact that by controlling the rate of cooling of the alloy the degree of hardness may likel wise be cont-rolled. Also by determining the proper cooling mediumlthe period required for the alloy to obtain a -more stable state may be readily controlled.

A. better understanding of the invention may be had from the following description when taken in conjunction with the accompanying drawing, which shows afset of representative curves determined by plotting application mea January as, 192e. serial no. 83,177.

tensile strength in kilograms per square milllmeter as ordinates and days of aging as abscissa, when a lead-antimony alloy having 21/70 antimony treated in accordance with the method outlined in the previously referred to copending application is quenched or cooled in different media.

As outlined in the foregoing copending application, the proper proportions of lead and antimony are combined to form a solid solution thereof which is reduced to a sub- -'lead and antimony is heated to a temperature slightly below the eutectic fusing temperature, which is not appreciably greater than 240 C. until a substantially homogeneous solid solution is formed. The alloy is then quenched to reduce the solid solution to a supersaturated solid solution and the alloy finally permitted to age during which period the solution assumes aysubstantially stable state. The present invention contemplates securing a supersaturated solid solu-4 a slow cooling, the result being totion by I change the resultantcharacteristics of the alloy, dependent upon the nature of the cooling step.

When it is desired to obtain an alloy y having a maximum degree of hardness and it is also desired to produce an alloy in which the hardness is attained in a rela` tivel short period of time, the alloy resultling rom the mixture of leadand antimony,

- graphy shows that by quenching the alloy in water which is at substantial room tem-u perature, an agehardena'ble alloy is prod uced having great 'tensile stren h as compared with the same alloy w en cooled slowly, as by cooling the alloy in different media represented by graphs B, C and D, as will be later described more in detail. lt should also be noted that the alloy attains its mai'rimum tensile strength in a comparatively short period of time.

Referring to graph B which illustrates the behavior of the ,alloy when cooled in a .substance or solution, such as glycerine, in

this case the alloy does notfattain as high a tensile strength as the alloy quenched in water-nor does it attain'its maximum tensile strength in the same period ot time: other words, the time required for the alloy to attain its maximum tensile strength is longer than in thev case of the alloy quenched in water. llt is, ofcourse, advantageous to produce alloysr having various degrees of hardness or tensile strength which are par-` a substantially stable condition when cooled in air at room temperature. rllhis particular condition is illustrated in graph C of the xset of curves shown in the single ligure of the drawing. ltlere again the maximum tensile stre/ngth lattained by the allow is less than in the case of quenching the allow either in wateror allowing it to cool in glycerine. Also the period required for the alloy to attain its maximum hardness is considerably longer thanv in the case of the other two cooling media heretofore inentioned.

Graph D illustrates the behavior of the alloy when it is allowed to cool in an oil which is heated to substantially a tempera# ture slightl below the eutectic fusing temperature o the alloy resulting from the y combination of lead and antimony. ln pracao f tune for it to tice. thisstep inthe treatment ot the alloy,

has been accomplished by heatin the alloy 1n the oil to a temperature slightly below the eutectic fusing temperature of the alloy and allowing the thus immersed alloy and the oil to assume substantially room temperature. The rate of cooling is thus considerably slower than in the case of the quenching of the alloy in water or cooling ,it in other cooling media heretofore mentioned, and produces a resulting alloy having a considerably lower tensile strength and requiring a-,considerably longer period of ,attain its maximum tensile strength. I Y

After the alloys are cooled to substantially room tem erature in Ia cooling media selectvedto pro uce in the resulting alloy the deremesa sired mechanical and other characteristic properties, it is allowed to age. Aging may take place at any temperature below the temperature of appreciable crystal growth of the components of the alloy, believed for lead antimony alloys of the type susceptible to improvements to be about 100 C. lln practice a good temperature is found to be around room temperature. d

rllhe term slow cooling as used in the foregoing description and the appended' claims refers to the step in the process of treating age hardenable alloys in which the alloy Ibecomes supersaturated being carried out at a rate such that the alloy assumes a more stable state subsequent to its heat treatment at a rate different from that resulting when the same alloy is quenched in water j l at substantially room temperature, the result being to produce an alloy having dierent characterlstic properties.

What is claimed is:

1. A process for controlling the charact-er istics of hardenable alloys, which consists in heating a solid alloy for Aa period ot time at a high temperature andcausing the alloy to. attain a supersaturated condition at a controlled rate. r

2. A process for controlling the characteristics of hardenable alloys, which consists in heating a solid alloy at a high temperature until a substantially homogeneous solid A solution is formed, cooling the alloy at a controlled rate to produce a supersaturated solid solution, and allowing the alloy to assume a substantially stable condition.

3. A method of controlling the rate of hardening of age hardenable alloys, which consists in reducing an alloy to a substantially homogeneous solid solution, cooling the alloy at a controlled rate, and aging.

4. A process for controlling the characteristics of hardenable lead alloys which consists in heating a solid alloy for a period of time at a high temperature, and causing the alloy to assume a supersaturated condition` in media having diEerent cooling properties.

5. A rocess of making an 1m roved lead alloy, which consists in adding alloying matter to lead, heating the solid alloy at a high temperature and reducing the resulting alloy to a supermtnrated solid solution, by cooling the alloy in a cooling medium having heat absor tion properties different from water.-

loying matter to lead, formin the res 11g alloy into solid solution, an

reducing `the said alloy to a. supersaturated solution byl antirnony alloy, which consists in heating a solid alloy to .a temperature high enough to allow the antimony present to enter solid process-lof making an improved leadantimony alloy, which consists in addixgalsolution, cooling the alloy slowly until it assumes a supersaturated condition and aging.

8. A process for making an improved leadantimony alloy, which consists 1n heating a solid alloy at a temperature of 240 C. for a period of time, and cooling the alloy slow- In witness whereof I hereunto subscribe 10' my name this 20th day of January, A. D. 1926.

REGNALD SCUTT DEAN. 

